Thousands of children who were told they may have a peanut allergy could be given the all-clear thanks to Manchester scientists.
About one in 10 children who are tested using existing technology are advised to avoid eating food with nuts.
But research at Wythenshawe Hospital found that only one in 50 children actually have an allergic reaction to peanuts.
Peanut allergy can be fatal and was thought to be one of the most common food intolerances in children.
The Manchester research was used by Swedish scientists who produced a blood test which is 95% accurate in diagnosing peanut allergy.
Prof Adnan Custovic who led the study with researchers from Manchester University, said: "The majority of 'so-called' peanut intolerant children had no reaction after eating them.
"The fear of possible reaction markedly reduces the quality of life among peanut-allergic patients and their families. However, avoiding peanuts only makes sense if a child is really allergic.
"The new diagnostic test which accurately discriminates peanut allergy from tolerance will mean we can target avoidance to those patients really at risk, and remove the considerable stress that comes from the many false positive sensitivity tests."